Effects of Eugenol-Loaded Chitosan Biopolymer Nanoparticles on CYP51a and CYP51b Expression in Aspergillus fumigatus

Aspergillus fumigatus is a pathogen responsible for invasive aspergillosis and the main leading cause of death in immunosuppressed individuals. The present study aimed to evaluate the impact of eugenol-loaded chitosan nanoparticles on the expression of CYP51a and CYP51b, two well-known genes responsible for triazole drug resistance in A. fumigatus.

The minimum inhibitory concentration (MIC) of eugenol-loaded chitosan nanoparticles, chitosan, eugenol, and itraconazole was determined based on the Clinical and Laboratory Standards Institute M38-E3 method at concentrations of 4.6-2400, 11.7-12000, 2-2048, and 1-256 μg/mL, respectively. The expression of CYP51a and CYP51b was evaluated in A. fumigatus exposed to 0.5, 1, and 2× of MIC concentration of NPs and itraconazole using the real-time polymerase chain reaction.

The obtained results showed that eugenol-loaded chitosan nanoparticles sucessfully reduced A. fumigatus fungal growth at 300 μg/mL concentration. MIC of chitosan, eugenol, and itraconazole was measured to be 6000, 256, and 4 μg/mL, respectively. The results of real-time PCR also revealed that eugenol-loaded chitosan nanoparticles increased the expression of both CYP51a and CYP51b in a dose-dependent manner. The expression of fungal CYP51a and CYP51b at mRNA level was significantly increased 1.26, 1.93, and 3.1-fold as well as 1.2, 2.1, and 2.4-fold at concentrations of 150, 300, and 600 μg/mL, respectively (p<.05). However, it seems that the prepared nanoparticles had a lower impact on the expression of these genes compared to itraconazole.

Overall, these findings suggest that the treatment of A. fumigatus with eugenol-chitosan nanoparticles could increase the expression of the CYP51 gene, suggesting the anti-fungal property of these nanoparticles.